Recent Submissions

  • Drivers of spatio-temporal dissimilarity in community composition: temporal changes in land use and environmental heterogeneity.

    Peláez Zapata, Oscar Eduardo (Universidade Estadual de Maringá. Departamento de Biologia. Programa de Pós-Graduação em Ecologia de Ambientes Aquáticos Continentais., 2020)
    Biodiversity encompasses multiple aspects or facets changing in space and time. Before a loss of biodiversity in response to anthropogenic impacts it is of the utmost importance to determine what facets of biodiversity are altered and the determinants of such changes. By using information from species abundance, their evolutionary relatedness, and ecological traits we determine how the dissimilarity in composition of fish communities is influenced by temporal changes in land use and changes in environmental heterogeneity across space. In the first approach, we can see that changes in land use over time affected mainly the substitution of evolutionary lineages and functional traits. In the second approach, we find evidence of taxonomic and functional homogenization over time, likely following a decrease in diversity of traits related to habitat use. Furthermore, we found that ecological traits contributed differently to the changes in functional composition as well in their response to environmental heterogeneity. These results support recently evidence showing that anthropogenic impacts are driving changes in biological communities through a taxonomic and functional homogenization.
  • Variáveis relacionadas com a distribuição regional, dominância e estruturação de comunidades de peixes em riachos.

    Oliveira, Fagner Junior Machado de (Universidade Estadual de Maringá. Departamento de Biologia. Programa de Pós-Graduação em Ecologia de Ambientes Aquáticos Continentais., 2020)
    Different ecological processes (e.g., rescue effect, environmental filtering, limiting similarity and dispersal) shape the structure of ecological communities. These processes, which are related to the theories of metapopulation and metacommunities, guided this study. For this purpose, data from fish communities in streams in the Upper Araguaia river basin (Mato Grosso and the Goiás States, Brazil) were used. It was observed that the regional distribution of fish species was modelled according to niche attributes (position and breadth), body size, trophic position, and swimming capacity. The results indicated that average abundance, niche position and niche amplitude predict the regional distribution of the species. Taken together, these results suggest the importance of metapopulation dynamics and niche-based processes explaining the regional distribution of species in the studied system. At another time, it was tested whether the abundance of subordinate species (i.e., any species that are not dominant in a local community) was correlated with the functional distance between dominant and subordinate species. In the results, a negative relationship between these quantities and that the subordinate species had larger body sizes compared to the dominant species in the local communities. These results also suggest that species filtering is more important than the interspecific competition to explain the patterns of species abundance distribution. In this study, was analyzed the relative importance of local environmental, landscape and spatial variables in structuring fish communities in streams of “veredas” (small wetlands in the Cerrado). The local environmental variables, after controlling the effect of space, were clearly more important than those obtained at the landscape scale. In view of the observations, it is concluded that the use of landscape data, in studies seeking environmental correlates of local community structure, should not occur at the expense of obtaining local variables (mainly those related to the habitat structure). The results of the three investigations in this study shown the predominant role of local environmental filters in the structuring of the fish communities analyzed. Species with high niche amplitude tend to have wide regional distributions and small-bodied ones tend to be locally dominant.
  • Predação e estruturação de habitat por macrófitas modificam a diversidade taxonômica e funcional do zooplâncton.

    Deosti, Sabrina (Universidade Estadual de Maringá. Departamento de Biologia. Programa de Pós-Graduação em Ecologia de Ambientes Aquáticos Continentais., 2020)
    In Neotropical rivers the predation by fish and the structuring of the habitat by macrophytes influence the dynamics of the zooplankton community, altering the richness and composition of species and the richness and functional composition of the zooplankton and thus the functioning of the ecosystem. We analyzed the influence of macrophytes bank structure and predation by forage fish species on taxonomic and functional zooplankton diversity, estimated by different diversity indices (taxonomic and functional richness, taxonomic beta diversity and functional beta diversity). Thus, we assume that different levels of macrophytes structure and fish predation will alter the taxonomic and functional composition of the zooplankton (alpha and beta) between the analyzed points. Beta diversity was split into two distinct components, turnover and nesting. The zooplankton species richness was positively associated with the macrophytes richness and the macrophytes diversity. In turn, the functional richness of zooplankton had a positive association with fish richness and macrophytes richness. For the variation of total taxonomic beta diversity of zooplankton, the Generalized Dissimilarity Modeling (GDM) explained 32.58% of the total among the predictor variables. The macrophytes biomass represented the taxonomic turnover. The variation in total functional beta diversity of the zooplankton explained 9.98% by the GDM model. The abundance of fish represented the functional nesting. Macrophytes structure represented the taxonomic components and predation represented the functional components. The limnological heterogeneity of the coastal region of the Bay River made possible the colonization by multispecies macrophytes banks, influencing the alteration of the fish and zooplankton community and the more heterogeneous the environmental conditions, the greater is the capacity of colonization of different species, which can present different functional traits. The results indicate the importance of maintaining heterogeneous locations, the need to preserve the tributaries in river floodplain systems as they serve as nursery for fish spawning and contribute to a greater richness of fish, which causes an increase in the functional diversity of zooplankton.
  • Effects of dam operation on stability, species interactions, and the mechanisms underlying the synchrony of fish in reservoirs.

    Baumgartner, Matheus Tenório (Universidade Estadual de Maringá. Departamento de Biologia. Programa de Pós-Graduação em Ecologia de Ambientes Aquáticos Continentais., 2020)
    The construction of dams is among the main anthropogenic impacts in natural freshwater systems. The first consequence of impoundments is the formation of reservoirs upstream, which represents a completely new environment compared to the natural river. In addition to this primary impact, the variations in the reservoir water level may be considered another facet of disturbances. Although several studies investigated the processes that occur in reservoirs, there is a shortfall regarding the effects of the dam operation scheme on ecosystem health. Most dams are designed to operate under two almost contrasting schemes: storage (STR) and run-of-river (ROR). These alternative operation schemes result in very different temporal variations, with STR reservoirs presenting rapid fluctuations while ROR reservoirs have a relatively constant volume. Likewise, this difference in the temporal dynamics of water level likely affects the stability of these ecosystems. In order to investigate how the dam operation scheme could affect the temporal stability of freshwater ecosystems, we used the fish communities from two reservoirs in the Iguaçu River that operate under contrasting schemes. The hypothesis was that the STR reservoir would be less stable, considering the environmental heterogeneity created by frequent water level variations, and the interactions among species would be less important for the structure of the resident fish community. In the first approach, the focus was on stability in terms of the ability to resist and recover (i.e., resistance and resilience) to disturbances. In the second approach, empirical data and simulations were used to assess which mechanism (species interactions, environmental or demographic stochasticity) underlie the synchrony of fish communities. Contrary to the expectation, the results showed the ROR reservoir as less stable than the STR, and the mechanisms underlying species synchrony coincided between reservoirs but played opposite roles. More specifically, the temporal dynamics imposed by ROR operation may have weakened the species-environment relationships, which led to a less stable community. Although the results were consistent, they were only primary evidence and such cause-effect relationships between dam operation and its effects on ecosystem stability require further investigations.
  • Abordagem multimétrica na avaliação da integridade ecológica : fundamentos conceituais e aplicações.

    Ruaro, Renata (Universidade Estadual de Maringá. Departamento de Biologia. Programa de Pós-Graduação em Ecologia de Ambientes Aquáticos Continentais., 2019)
    The use of multimetric indices (MMIs) to assess ecological conditions in aquatic environments has been applied globally. These indices are practical tools that incorporate various biotic metrics at different levels of biological organization. However, criticism has been directed to the use of MMIs, especially regarding the methodological criteria applied in the process such as related to metric selection and scoring and identification of reference conditions that consider all sources of ecological integrity disturbance. A review of the scientific literature was carried out to evaluate processes of creation and validation of MMIs worldwide. The criteria used by scientists to identify reference conditions, metric selection and scoring, the main metrics globally used in MMIs, and the challenges in applying these indices were verified. It was identified whether nonnative species have been considered as a source of degradation of ecological integrity in the MMIs application. The results indicated that there are no common criteria for determining reference conditions, for metric selection and scoring, which makes it difficult to compare different programs and regions, and to develop or improve future MMIs. The results showed that metrics related to species richness were most frequently used in MMIs applied worldwide, thus, it represents a consistent response pattern in the assessment of ecological conditions. The results also indicate that differentiating natural variability from anthropogenic impacts was evidenced as the major challenge in the MMIs creation and application. The review of the scientific literature indicated that biological invasions are neglected in ecological integrity assessments, as nonnative species are rarely considered as a disturbing factor in identifying reference conditions and species origin metrics are not widely used in MMIs. The results presented in this review may promote the advancement and improvement of MMIs as bioassessment tools.
  • Fatores determinantes das diversidades beta taxonômica e funcional do zooplâncton em planícies de inundação neotropicais.

    Amaral, Diogo Castanho (Universidade Estadual de Maringá. Departamento de Biologia. Programa de Pós-Graduação em Ecologia de Ambientes Aquáticos Continentais., 2020)
    Freshwater ecosystems are changing their natural conditions, influenced and accelerated by human activities. These processes are capable of changing the hydrological regime and the composition of the communities, letting the future of aquatic biodiversity unknown. The construction of dams has been one of the main factors responsible for environmental changes, such as nutrients depletion, increased water transparency and loss of biodiversity in freshwater ecosystems. The aim of our study was to analyze the functional and taxonomic dissimilarity of the zooplankton community and its drivers in response to the effect of the hydrological cycle (drought and rainy), in two highly distinct floodplains, the Upper Paraná River (river with a cascade of dams) and the Amazon. A total of 72 samples were collected (16 AMA dry and 16 on rainy and 20 PAR dry and 20 on rainy) from zooplankton communities as the response variable, phytoplankton as a predictor of food, fish as a predictor of potential predators and limnological variables. Were calculated β-Total diversity and partitioned in the components β-Repl and β-Rich (taxonomic and functional approach). We expect that environmental heterogeneity is going to drive higher values of beta diversity. In sequence, distance-based redundancy analysis (db-RDA) was calculated using the distance matrices generated in the functional and taxonomic beta to assess which are the determinants of zooplankton beta diversity. Thus, we hypothesized that biotic interactions will have stronger relationships with zooplankton dissimilarity during the drought and, limnological variables and spatial component will be more important during rainy season. Greater environmental heterogeneity was found in the Amazon floodplain and also in the dry season. The beta functional and taxonomic diversity of zooplankton showed a similar relationship between the floodplains and between the hydrological periods, represented by the β-Repl component, except for the drought season in the Upper Paraná River, where the functional diversity showed the lowest values, undetected by the taxonomic approach. The factors that influenced the zooplankton beta functional and taxonomic diversity in the two floodplains were different depending on the hydrological period, reflecting once again the difference in environmental heterogeneity and the strength of hydrodynamics within each plain. The analysis of the species and functional traits distribution and, which are the variables structuring this distribution is extremely important to analyze ecosystem processes and services, especially in impacted environments such as the Upper Paraná River floodplain, and a floodplain so biodiverse as the Amazon, and even so, with the prediction of the construction of numerous dams in its hydrographic basin. We reinforce the importance of periodic flooding in these floodplains, for the maintenance of biodiversity and ecosystem services over time, and in this way, prevent biotic homogenization, and consequently, conserve these aquatic ecosystems.
  • Aspectos ecológicos e taxonômicos da fauna ectoparasitária de Plagioscion squamosissimus (Heckel, 1840) (Sciaenidae) no rio Tapajós, Bacia Amazônica, Brasil.

    Capparros, Eloiza Muniz (Universidade Estadual de Maringá. Departamento de Biologia. Programa de Pós-Graduação em Ecologia de Ambientes Aquáticos Continentais., 2019)
    Plagioscion squamosissimus (Heckel, 1840) (Sciaenidae), known as “corvina” is a native species of Amazon basin and it is a model for studding their parasites. Intending to analyze ectoparasites ecological aspects, such as distribution and interactions, gills of twenty specimens were analyzed, from rio Tapajós, in the region of Santarém-PA, Brazil. Ecological analyzes considered distribution of parasites between host specimens and also microhabitats occupied by ectoparasites. Eighteen ectoparasites species were founded, fourteen monogenetic and four copepods. Considering species abundance, monogenetic were the dominant group and Euryhaliotrema thatcheri was the most abundant in all analyzed hosts. There was a significate correlation between some parasite species abundance and prevalence with total length and host condition factor. Each species of parasite presented an aggregate distribution pattern. The community of P. squamosissimus ectoparasites were interactive. Considering the distribution of the species in the gills, there was a significant difference in the composition between arches, segments and regions. It is suggested that this distribution is related to factors related to microhabitat, such as water flow and area available for fixation of parasites, as well as the structures of fixation of each species and interactions such as positive associations and competition. During the investigation of the material, specimens that differed from the species already described were founded, so three new monogenetic species were proposed, belonging to the genus Aetheolabes, Anakohnia and Euryhaliotrema, based on their morphological characteristics.
  • Efeitos do El Niño Southern Oscillation (ENSO) nas assembleias de peixes de uma planície de inundação Neotropical.

    Alves, Jonas Campaner (Universidade Estadual de Maringá. Departamento de Biologia. Programa de Pós-Graduação em Ecologia de Ambientes Aquáticos Continentais., 2020)
    We evaluated the effects of El Niño Southern Oscillation in the fish assemblages of the upper Paraná River floodplain. Specifically, we tested if: (i) reservoirs regulate ENSO effects on the hydrometric level in the rivers that compose the plain (Rio Paraná – intensely dammed and Rio Ivinhema – not dammed); (ii) ENSO events influence the structure of the fish assemblages of the study rivers; and that (iii) the hydrometric level and the ENSO events will act synergistically on the structure of the fish assemblage of the Rio Paraná and Rio Ivinhema. ENSO data was gathered at the National Oceanic and Atmospheric Administration (NOAA), using as proxy the “Oceanic Niño Index” (ONI). Water level data were gathered from the hydrological stations located in the sampled area. Fish samplings were carried out quarterly between the years 2000 and 2018. In general, ENSO events were correlated with the hydrometric level of the Rio Paraná and Rio Ivinhema, but with lower correlation for the Rio Paraná, probably due to the effects of dams upstream the plain. The fish assemblages of the Rio Paraná and Rio Ivinhema presented distinct structures, and the ENSO events appeared to influence this differentiation. Migratory species were negatively correlated with ONI, but the greatest abundances were found one year after the events of El Niño ("Lag" of one year). Higher values of the attributes of the fish assemblages were recorded for the Rio Ivinhema, in all events of ENSO (La Niña, Neutral and El Niño), probably because it presents more pristine conditions. The hydrometric level and the ENSO events act synergistically, but distinctively in the study rivers, which should be related to their degree of impacts. Thus, the influence of ENSO in the studied area is apparently minimized, especially in the Rio Paraná, due to the flow control imposed by dams located upstream of the area.
  • A diversidade funcional da assembleia de peixes em uma planície de inundação Neotropical: variações com eventos de El Niño Oscilação Sul (ENSO).

    Andreotti, Gustavo Faccin (Universidade Estadual de Maringá. Departamento de Biologia. Programa de Pós-Graduação em Ecologia de Ambientes Aquáticos Continentais., 2020)
    El Niño Southern Oscillation (ENSO) is a natural phenomenon that generates El Niño and La Niña events worldwide. Among the consequences caused by this climatic fluctuation, there are changes in the rainfall regime, which can trigger in times of extreme drought or extreme flood in freshwater environments, such as floodplains. The floodplain flood phases cause homogenization between the different environments, which also cause the homogenization of the fish assemblage in these floodplains. Among the rivers affected by ENSO is the Rio Paraná and the floodplain associated with its upper stretch, the upper Rio Paraná floodplain (UPRF). We aimed to study if El Niño phenomena change the functional diversity of fish in the floodplain between different environments, lakes and rivers. The results answered the hypotheses that: 1. El Niño events intensify floods in UPRF and, consequently, promote a functional homogenization of the fish assemblage; 2. Different functional guilds will be favored in times of El Niño or La Niña. The measurement of ENSO was obtained by the Oceanic Niño Index (ONI), while the hydrometric level of the upper Rio Paraná was obtained by daily measurement on a hydrometric ruler. The fish were collected with gillnets in different environments of the floodplain, lakes and rivers, being grouped in reproductive and trophic guilds, used to calculate indices of functional diversity. It was tested how ONI affects the hydrometric level of the upper Rio Paraná (Pearson's correlation); how ENSO affects the functional composition of floodplain fish (PCoA; PERMANOVA), as well as the effect of homogenization; which functional guilds are favored in El Niño or La Niña events and whether there is an additive effect of ONI and hydrometric level on the functional composition of the floodplain fish. The hydrometric level presented a positive correlation with ONI, indicating that El Niño events cause flooding in the upper Paraná River, while La Niña drought. The effect of El Niño's functional homogenization on fish was more visible in lakes, with rivers being less affected by ENSO, and floods were not intense enough to homogenize these two types of environment, this may be the same for other floodplains where ENSO acts in the same way. Fish with parental care and invertivores were favored in El Niño events, while herbivorous and piscivorous fish were favored in La Niña events. Migratory fish appears to respond one year after these climatic events, as they have a long-life cycle. The additive effect of ENSO and hydrometric level on the functional composition wasn’t found, because other regional and local factors can influence this interaction. However, even with these factors, the fish assemblage from the floodplain still responds to these climatic fluctuations, being more homogeneous in El Niño events than in La Niña events.
  • Nematoides como indicadores de alterações ambientais em um rio com diferentes níveis de impacto antropogênico.

    Lehun, Atsler Luana (Universidade Estadual de Maringá. Departamento de Biologia. Programa de Pós-Graduação em Ecologia de Ambientes Aquáticos Continentais., 2020)
    Changes in the biodiversity of parasites communities can be used as indicators of the healthy ecosystem as they reflect environmental impacts through their responses to changes in habitat. Thus, the aim of the study was to investigate the potential use of parasites from Geophagus brasiliensis as bioindicators of environmental changes. Three sample points were determined of rio Iguaçu with different degrees of environmental impact. Among 69 specimes analyzed of G. brasiliensis, 32 (46.3%) were parasitized by at least one parasite. A total of 56 specimens of endoparasites belonging to the phylum Nematoda were collected. The abundance of nematode species was significantly higher in fishes collected in point 3 (Kruskal-Wallis2;69 = 8.62; p = 0.01) and species composition between points were significantly different (F = 6.95, p = 0.002). There was no significant difference in relative condition factor (Kn) of G. brasilienses between the points (F2;66 = 2.54; p = 0.08) there was no correlation in Kn and abundance of nematodes (rs = 0.1; p = 0.4). The lower abundance of nematodes was observed in point 1 (critically degraded), due to this environment showing changes in abiotic factors, represented in the relatively high values of conductivity and phosphorus when compared with points 2 and 3 (moderately degraded).The results obtained in the present study indicate that the parasitic community of G. brasiliensis is characterized by low diversity in polluted locations, thus the absence of certain species of parasites and the occurrence of nematode species demonstrated a variation in response to the pollution gradient.
  • Filogenia de Geophagini (Cichliformes: Cichlidae: Cichlinae) utilizando a anatomia do encéfalo.

    Oliveira, Rianne Caroline de (Universidade Estadual de Maringá. Departamento de Biologia. Programa de Pós-Graduação em Ecologia de Ambientes Aquáticos Continentais., 2020)
    Several studies have presented phylogeny of Geophagini based on morphological and molecular characters; however, neuroanatomical characters have not been explored for the tribe yet. Fish encephalon shows interspecific morphological variation, even in related groups, and can be used to build cladograms. The phylogeny of Geophagini is presented using the neuroanatomical characters mapped on a previous cladogram. This approach showed how the encephalon of Geophagini species have diversified among clades and how ecological features of some species can be related to changes (increase or decrease) of a particular structure. The morphological description of the encephalon of Geophagus sveni was also performed, with an illustration of the major encephalon structures and the origin of the cranial nerves, as well as a comparison of the morphometric differences between males and females.
  • A complexidade do habitat e a variação individual na dieta e na morfologia de uma espécie de peixe associada à macrófitas.

    Cardozo, Ana Lúcia Paz (Universidade Estadual de Maringá. Departamento de Biologia. Programa de Pós-Graduação em Ecologia de Ambientes Aquáticos Continentais., 2020)
    Generalist species can be composed of specialist individuals, who use a small part of the population's niche. This process is known as individual specialization and can involve changes in diet and morphology. In this study, we hypothesized that individual variations in the diet and morphology of fish associated with macrophytes are related to the habitat’s complexity and greater levels of individual specialization will be found in the intermediate levels of macrophyte biomass. Fish and macrophytes were sampled in 30 multispecific macrophytes stands with different biomasses in a 13.7 km stretch of the rio Baía (Paraná River floodplain). Habitat complexity was assessed using the biomass of aquatic macrophytes (five stands with low biomass, five with intermediate biomass and five with high biomass were selected) and the fish species used in this study was Moenkhausia forestii. The individuals' diet was evaluated using the volumetric method, and the morphology through 18 linear measurements and six area measurements. To assess individual specialization in the diet, the Specialization Index (IS) and the NODF nesting index were used. Individual morphological specialization was assessed using ecomorphological diversity for each level of macrophyte biomass. Correlations between diet and morphology were assessed using the Mantel test. IS and NODF values indicated greater individual specialization in the diet in macrophytes stands with low biomass. The greatest individual morphological specialization was found in macrophytes stands with intermediate biomasses. The Mantel test showed that there was no significant correlation between diet and morphology. The individual specialization of M. forestii diet is related to the increase in competition, mainly intraspecific, intensified by the low availability of resources in low biomass stands. Morphological specialization, in turn, is related to greater availability and accessibility to resources within the intermediate biomass stands, where there are ideal conditions for increasing richness and abundance of resources and little structural complexity when compared to high biomass stands.
  • A diversidade de macrófitas altera a comunidade de invertebrados e a dieta de peixes.

    Yofukuji, Kátia Yasuko (Universidade Estadual de Maringá. Departamento de Biologia. Programa de Pós-Graduação em Ecologia de Ambientes Aquáticos Continentais., 2020)
    The diversity of aquatic macrophytes provides different local conditions, containing more microhabitat than homogeneous systems, thus supporting diverse biotic communities. Considering that the diversity of these plants can affect the invertebrate community and, consequently, the associated fish diet, this study assessed the influence of macrophyte diversity on the abundance, richness, and diversity of invertebrates, and the diet of Moenkhausia forestii. Fish, invertebrates, and macrophytes were sampled in macrophyte stands with different diversities, distributed along with a 14 km extension of the coastal region of Rio Baía (Upper Paraná River floodplain). The stands were separated into low, medium and high diversity, and they all had biomass that did not differ significantly. The invertebrates associated with the macrophytes and those consumed by M. forestii were identified and counted. Differences in abundance, richness, and diversity of invertebrates between levels of macrophyte diversity (low, medium and high) were tested using an ANOVA. Differences in the composition of the M. forestii diet were tested using a PERMANOVA, and feeding selectivity was calculated using the Ivlev index. Richness, diversity, and abundance of invertebrates were greater in high diversity macrophyte stands, however, for abundance, there was no significant difference between the levels of macrophyte diversity. The diet of M. forestii differed significantly between stands, and aquatic plants were the most used resource in low diversity. Invertebrates were dominant in high diversity, while aquatic plants and invertebrates were important in medium diversity of macrophytes. These results indicate that invertebrate communities were influenced by the diversity of macrophytes since richer and more diverse communities were also associated with more diverse stands of these plants. Changes observed in the diet of M. forestii were also associated with the diversity of macrophytes. In a scenario where involving changes in the attributes of these plants, and these stands become dominated by one or a few species of macrophytes, it is expected that this will reflect on other trophic levels, even at a local scale.
  • Sensoriamento remoto orbital para o estudo das interações ambiente-ictiofauna em um reservatório Neotropical.

    Schmitz, Marcelo Henrique (Universidade Estadual de Maringá. Departamento de Biologia. Programa de Pós-Graduação em Ecologia de Ambientes Aquáticos Continentais., 2020)
    The differential distribution of productivity in reservoirs has consequences for the fish assemblage, influencing spatially in its distribution, along a longitudinal gradient. Following the hypothesis that the spatiotemporal dynamics of chlorophyll a and turbidity influence the distribution of the fish assemblage in the Sobradinho reservoir, BA, three predictions were tested: i) Whether the spatiotemporal variations of these variables, determined by digital processing of remote sensing images, follow the spatial zoning pattern described in the literature, for large reservoirs; ii) Whether with the increase in distance, in kilometers, from the collection points to the dam, there is an increase in the total abundance of fish; and iii) If, with the increase in productivity, represented by higher concentrations of chlorophyll a and turbidity, there is an increase in the abundance of fish (total or by trophic guild). The sampling was distributed in five periods, between April 2008 and July 2009, with at least one collection being carried out in each zone of the reservoir, fluvial, transition and lake, in each period. Bands 2 and 3 of scenes from the Landsat-5 satellite were selected, in which the chosen limnological variables show their peak of reflection. With the values of the collections in situ and the reflectance of the scenes, an interpolation was performed and, later, thematic maps of each of the variables were elaborated. The chlorophyll a and turbidity values of the ichthyofauna collection points were extracted from the interpolations. To analyze the existence of the longitudinal gradient, Spearman correlation analyses were performed between the value of the limnological variables and the distance from the collection point to the dam, obtained by extracting a longitudinal profile of the reservoir. To search for associations between limnological variables and ichthyofauna, Spearman's correlation analyses were performed with the value of the variables and total abundance and by trophic guilds. Also, the analyses were carried out dividing the collection points according to the reservoir area and the rainfall regime (dry and full). The Sobradinho reservoir showed a pattern of productivity zoning consistent with the typical pattern of large reservoirs. This zoning had a strong association with the distribution of fish abundance in the Sobradinho reservoir. There was an association between the abundance of fish in the lake area and the seasonal increase in productivity, with a remarkable decrease in abundance during the dry months and an increase in abundance during the floods. However, in the river zone, excess turbidity acted as a limiting factor. High values of this variable, also showing a greater flow of water, may have favored the dispersion of organisms to places of lesser environmental stress, reducing the abundance of fish in this region during floods. However, in general, the fluvial zone showed the highest abundances, exhibiting the well-known fluvial> transition> lacustrine pattern. The presence of favorable characteristics in the river zone, such as seasonal flooding and greater environmental heterogeneity, may have contributed to this result.
  • Relações filogenéticas em Geophagini (Acanthopterygii, Cichlidae), utilizando caracteres miológicos.

    Deprá, Gabriel de Carvalho (Universidade Estadual de Maringá. Departamento de Biologia. Programa de Pós-Graduação em Ecologia de Ambientes Aquáticos Continentais., 2019)
    Although several studies have dealt with the description of morphological characters in Cichlidae, usually aiming for phylogenetic inference, little attention has been given to their musculature. The complete striated musculature of a cichlid species, Geophagus sveni Lucinda, Lucena & Assis, was described for the first time, with illustrations of all muscles and a protocol for the dissection of specimens. The striated musculature of at least of species of each genus in tribe Geophagini, among other cichlids, was compared, and 98 characters were described with the purpose of analysing their relation with the group’s phylogeny. This character matrix was employed to produce two unconstrained phylogenetic analyses, one weighted and the other unweighted. The myological characters were mapped upon a pre-existing phylogenetic hypothesis, for understanding the correlation among the characters and trophic specialisations of each taxon. The conclusion is that Geophagini specialised in sifting substrate (winnowers) tend to present a few convergent adaptations, manifested in the shape and degree of development of muscles such as adductor mandibulae, levator arcus palatini, dilatator operculi, adductor branchialis 1 and obliqui ventrales 1–2. This study facilitates future investigations on the functions of the striated muscles in fishes and their role in the processes of adaptive radiation, i.e., functional diversification.
  • Resposta da comunidade zooplanctônica e efeitos em cascata à predação: uma abordagem experimental.

    Silva, Heloisa Santos (Universidade Estadual de Maringá. Departamento de Biologia. Programa de Pós-Graduação em Ecologia de Ambientes Aquáticos Continentais., 2019)
    The presence of a predator can play a key role in structuring ecological communities through both predation and their indirect threat. Predation risk in aquatic systems is often assessed by prey by chemical cues, either those released by prey or the predator itself. Through an experimental approach, this study sought to evaluate the influence of a chemical signal or the effective presence of a top predator (omnivorous fish) on the variation in the abundance of zooplankton communities, and if interference from these higher levels occurs, trophic cascade over the protoplankton community. The results showed the ability to induce a chemical signal and the perceived threat of predation of (zooplankton microcrustaceans) by predatory fish (Moenkhausia bonita). The presence of chemical cues made it cause to seek refuge from prey, demonstrating the indirect influence of a piscivore on the structure of a trophic cascade and its impacts on communities of protist ciliates, present at lower levels of a chain.
  • Dinâmica da comunidade de algas perifíticas em lago temporário do semiárido.

    Fernandes, Ubirajara Lima (Universidade Estadual de Maringá. Departamento de Biologia. Programa de Pós-Graduação em Ecologia de Ambientes Aquáticos Continentais., 2019)
    Temporary ponds are the most common ecosystems in the world and have a seasonal dynamic that can be influence the structure of biological communities living in these environments. Although they are common ecosystems in semiarid regions, its functioning and the way it influences the ecology of the species that inhabit these environments are still incipient. Therefore, the successional dynamics of the periphytic microalgae was studied in order to add information about the structure of this community of primary producers in this environment. A 30-day in situ experiment was carried out in a temporary pond located in the rural area of the municipality of Pacatuba (Ceará State, Brazil). Changes in the abundance of periphytic microalgae were observed in a successional period that showed the occurrence of alternative stable states in this community. Changes in ecological attributes (e.g. richness, diversity, equitability and biomass) in the early days of colonization indicate that the successional trajectory was strongly influenced in this period. We can observe three alternative states: (I) corresponding to the largest abundance of Coelastrum proboscideum and related to the development of the other algae that make up the periphytic community; (II) stage represented by the highest abundance of Achnanthidium minutissimum, when the community reached its climax; (III) after the decline in the abundance of this diatom, the green algae resumed its increase in abundance, accompanied by the growth of other periphytic algae, thus evidencing the resilience of this community. We conclude that the community of periphytic algae is sensitive to small disturbances, especially those that may occur during the temporary lake drying period, directing this community to present different configurations during the successional period and reflecting in alternative stable states.
  • Efeitos de reservatórios em cascata à montante sobre os padrões espaciais e temporais de diversidade β de ciliados planctônicos em uma planície de inundação neotropical.

    Durán, Carolina Leite Guimarães (Universidade Estadual de Maringá. Departamento de Biologia. Programa de Pós-Graduação em Ecologia de Ambientes Aquáticos Continentais., 2019)
    In floodplain environments, dam construction can alter connectivity, sediment transport and water discharge in these systems, and cause a process known as biotic homogenization (i.e. reduction in beta diversity). Beta diversity (β diversity) is a fundamental component of biodiversity and changing species composition over time and space is not only a topic of theoretical interest but also has important implications for regional biodiversity planning. Considering this, the possible changes of taxonomic β diversity along a temporal and spatial gradient were investigated in two subsystems of a neotropical floodplain, one of them being impacted by dams and the other free of dams along its course. For the spatial analysis, the results contradict our prediction, so that the Paraná subsystem, strongly impacted by a series of upstream reservoirs, showed no tendency to reduce the β diversity, presenting a pattern similar to that observed for the non-impacted subsystem. In this sense, a process of biotic homogenization was not observed for the community of ciliated protists downstream of the buses. In addition, the turnover component was the most important, showing a high environmental heterogeneity in the studied systems. For the temporal analysis, there was a significant change in species composition from the first to the last year analyzed, only for the subsystem impacted by dams (Paraná), and this increase in β diversity over time was determined mainly by species loss.
  • Anfíbios e peixes são indicadores de diferentes hotpoints de biodiversidade na Mata Atlântica.

    Covre, Amanda Caroline (Universidade Estadual de Maringá. Departamento de Biologia. Programa de Pós-Graduação em Ecologia de Ambientes Aquáticos Continentais., 2019)
    The identification of consistent patterns of biodiversity that can be used to guide conservation actions has become one of the main objectives of Ecology. Therefore, the use of surrogate groups has highlighted in recent years. This approach is based on the assumption that the protection of a given taxon guarantees the safety of others in similar conditions, requiring less effort and /or financial investment. Its use is only feasible when the groups evaluated have high values of cross-taxon congruence and depends on the choice of well-known species, widely distributed and easily monitored. Considering that the presence of areas with high cross-taxon congruence between terrestrial and freshwater biodiversity has already been observed in tropical regions, it is possible for fish and amphibians to constitute good substitutes between them in the Atlantic Forest biome. Thus, we used geographic distribution data from bony fishes and amphibian species, as well as their functional characteristics throughout the biome, in order to evaluate the existence of cross-taxon congruence patterns and to identify if they are biodiversity surrogates. In this way we used spatial, morphological and ecological data were obtained from ichthyofauna and amphibiofauna for niche modelling of richness species and functional diversity, we used databases and bibliographical references; species presence / absence matrices were constructed; the functional diversity was calculated for the groups and the correlation between the values of richness and functional diversity of fish and amphibians was made through simple linear regressions. From the results it was verified that the highest values of fish richness and functional diversity are concentrated in the West Atlantic Forest, while those values for amphibians are located in the East. The regions of Serra do Mar and south of the Central Corridor were the only points that presented overlap between the groups. In this way, the obtained results offer valuable information that must be considered by the competent organs, responsible for the elaboration of strategies and plans of conservation and management of species.
  • Pterygoplichthys ambrosettii (Holmberg, 1893) (Siluriformes: Loricariidae): invasão, história de vida e impactos sobre o funcionamento do ecossistema.

    Silva, Jislaine Cristina da (Universidade Estadual de Maringá. Departamento de Biologia. Programa de Pós-Graduação em Ecologia de Ambientes Aquáticos Continentais., 2019)
    Biological invasions are among the greatest threats to global biodiversity, and in Brazil the introduction of non-native fish has become increasingly common. Due to this problem, studies on the biology of non-native species are necessary for the understanding of aspects related to biological invasions and successful establishments. However, the factors related to these processes still lack information, fact observed for the species of invasive fish Pterygoplichthys ambrosettii. This species is considered to be one of the most abundant in the floodplain of the Upper Paraná River, and its introduction is increasingly widespread, and yet much of its biology and natural history remain untested. Thus, the general objective of this thesis was to analyze aspects related to invasion, life history and impacts on the ecosystem by P. ambrosettii, in the upper Paraná River basin. First, the chronology of invasion of this species was analyzed by means of long-term data (1983-2017), in order to identify the main route or means of dispersion of this species in the basin. The second study aimed to know the life history of P. ambrosettii and its relations with its invasion and establishment. The third study provides a detailed description of the embryonic, larval and juvenile development, obtained from P. ambrosettii induced reproduction. The fourth study, through an experimental approach, analyzed the effect of the abundance of P. ambrosettii on the functioning of the invaded ecosystem. The historical invasion of P. ambrosettii confirms its status as introduced in the upper Parana River, possibly through aquarism, began to occur in the region as of 1997. It is currently dispersed and established throughout the basin, presenting high potential for invasiveness, which was confirmed in this study. In general, aspects of life history presented by this suckermouth armored catfishes, such as 1: 1 sexual ratio, moderate body size and fecundity, first maturation size, parental care, long embryonic development, large eggs and precocious larvae, maximize offspring survival, and guarantee their recruitment. In addition, specific egg characteristics, such as the ability to manage the use of endogenous oxygen and the adhesiveness, which reduce the friction within the nest, also cooperate for the resistance of the offspring, and consequently of the species. In addition to all the advantages already imposed by the biology of P. ambrosettii, it was observed that in high abundances, this can promote consistent effects on the cycling of nutrients in the ecosystem. The abiotic variables pH, dissolved oxygen and electrical conductivity were altered by treatments, as well as the primary productivity (chlorophyll-a and aquatic macrophytes), which presented high concentrations and biomass, as a function of the increase of nutrients (nitrogen and phosphorus) in the column of water. On the other hand, a reduction in the density and composition of protozooplankton were caused directly or indirectly by changes in water quality. At the end of the study, specific conditions of a eutrophic environment were observed. Thus, in view of the prospects of an invasive species, P. ambrosettii showed a very expressive model, with singular characteristics of life history and disturbances on the communities and functional ecosystem structure.

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